HB Computer Security | Aide Memoire
  • Introduction
  • Core Technical Skills
    • Core Skills
      • Linux
        • Getting to Know Linux
          • Using the Shell
            • Shells, Terminals, and Virtual Consoles
            • Choose your Shell
            • Shell Commands
              • Non-PATH Commands
              • Command History
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                  • Keystrokes for Navigating Command Lines
                  • Keystrokes for Editing Command Lines
                  • Keystrokes for Cutting and Pasting Text from within Command Lines
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                  • Keystrokes for Command Line Recall
              • Connecting and Expanding Commands
                • Piping Between Commands
                • Sequential Commands
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            • Shell Variables
              • Common Shell Variables
            • Aliases
            • Create your Own Shell Environment
              • Modification Ideas
          • Navigating the Linux File System (LFS)
            • Filesystem Commands
            • Listing Files and Directories
            • File Permissions and Ownership
              • Modifying Permissions with chmod
              • Modifying Default Permissions with umask
              • Change File Ownership with chown
            • Copying, Moving, and Removing Files
            • Finding Files
              • locate
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            • Downloading Files
              • axel
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                • User-Agent: Googlebot
          • Working with Text Files
            • Using vim and vi to Edit Text Files
              • Starting with vi
              • Adding Text
              • Moving Around in the Text
            • Text Manipulation
        • System Administration
          • Installing Linux
            • Installing from Live Media
            • Installing in the Enterprise
            • Partitioning Hard Disks
              • Tips for Creating Partitions
          • Account Administration
            • The root Account
              • Becoming root with su
              • sudo
                • The /etc/sudoers File
                • Granting sudo privileges
                  • visudo Guidance
                • Useful sudo Hints
            • Other Administrative Accounts
            • Standard User Accounts
              • Risks of userdel: Orphaned Files
          • Graphical Remote Administration
            • Cockpit
              • Installation Guide
            • Remote Desktop Protocol with xrdp
              • Installation and Configuration
            • Remote Desktop with vnc
              • Installation and Configuration
              • Running VNC as a System Service
          • Managing Running Processes
            • Listing Processes
              • ps
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              • htop
            • Backgrounding and Foregrounding
              • Starting a Background Process
              • Using Foreground and Background Commands
            • Killing and Recining Processes
              • kill and killall
          • Managing Software
            • Managing Software from the Desktop
            • Going Beyond the Limitations of Software Center
              • Debian Packages
                • Advanced Package Tool (apt)
                • Repositories
                • dpkg
        • Shell Scripting
          • Variables
            • Command Substitution
            • Arguments
          • Reading User Input
          • if, else, and elif
          • BOOLEAN Logic
          • Loops
            • for Loops
            • while Loops
          • Functions
          • Local Vs Global Variables
          • Summary
        • Securing Linux
      • Windows
        • Security Hardening
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  1. Core Technical Skills
  2. Core Skills
  3. Linux
  4. Getting to Know Linux
  5. Navigating the Linux File System (LFS)
  6. File Permissions and Ownership

Modifying Default Permissions with umask

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Last updated 1 year ago

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When you, as a regular user, create a file, it's given a set of default permissions of 664, while directories get 775. For the mighty root user, file permissions default to 644 and directories to 755. These defaults are influenced by the umask value. You can check your default umask value by typing umask like this:

umask

If you ignore the leading zero for the moment, your umask value is essentially a mask that hides what would otherwise be completely open permissions for a file (666) or a directory (777). A umask value of 002 means that directory permissions become 775, and file permissions become 644, assuming execute permissions are disabled by default for regular files as standard.

You can alter your umask value temporarily by using the umask command. Afterward, you can create files and directories to observe how the umask value influences permission settings.

Here are some examples:

If you want to change your umask value permanently, add a umask command to the .bashrc file in your home directory.

Default permission configuration example
Examples of different umask values